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Thank you.

Thank you. I thought that the GND in between L & R on the "out" section of the PCB was an isolated GND specifically for audio output. I assumed it was isolated from the digital realm of the PCB as a way to prevent potential noise. Looking at the schematic I can see they're all connected? What is...

Right. I was going by what was printed on the actual pcb, there are 2 gnd connections one the for Line in Right and the other for the Line In Left? Then there is only one gnd connection for both Left & Right outputs? (I call that one gnd connection for both audio outputs "Audio Out GND". Am I...

I'm using Teensy 4.0 with the Audio Board RevD. I am only using LIN, LINGND and LOUT, OUTGND now. Thank you. Tony

Thanks for reading. I am working on making a simple guitar buffer circuit that will connect to the Teensy Audio Board Rev D. Is it ok to connect RIN and LIN together for the buffers circuit output signal? The audio output GND of my buffer circuit connected to the RINGND and LINGND? Or is it...

Ok great. I am using INPUT_PULLUP. I appreciate your help on this, thank you.

I'm using the Encoder library, would that automatically set the HYS bit? (Does the library put every encoder pin into INPUT_PULLUP, hysteresis included?) Thank you.

Thank you for this info, I appreciate it very much.

Do you mean the P-Channel chip with the resistor and caps in my power input circuit? Thank you.

Thank you. It is mechanical, so I will be trying 10k pullups and 0.1uF caps. Using the implementation described here: https://www.build-electronic-circuits.com/arduino-rotary-encoder/

What built-in filtering are you referring to? Thank you.

Yes, that's what I'm trying. Thank you. (I'll find out how it works tomorrow) Thank you!

I'm only using the Rotary part of the encoder (without the push button switch) for 3 of them. The one connected in the schem does use the push button switch. The other 3 are remote (on a separate pcb). Thank you.

Hello, I am using some rotary encoders with the Teensy 4.0 and Audio Board. Should I use caps with the encoders? (In my schem. I haven't wired the 3 encoders on the left). Thanks for any advice. Appreciated. TonyAm

Thank you for the input.

Thank you. I tried your link but it didn't work. A "switch mode psu"? I will look into that too.

I have a circuit board that I've made for the Teensy 4.0 and Audio board. Currently using a 7805 with a 9V power adapter. The 7805 gets very hot, so thinking about using the muRata OKI-78SR-5/1.5-W36-C. https://www.lcsc.com/product-detail/C6134431.html?s_z=n_q_C6134431&globalKeyword=C6134431 (Q1...

Hello, Thanks for reading. Would I need to use a logic level shifter to convert the 5V logic levels (I2C) of the LCD's scl/sda lines to 3.3V in order not to damage the Teensy's scl/sda pins? Any recommendations for an easy to use Level Shifter for this scenario? Sincere Thanks, TonyAm

In case anyone else has questions about using external pullup resistors for the sad/scl lines when using the Adaruit MPR121 capacitive touch board, I have discovered that they already have built-in 10k pullup resistors, as described here: https://forums.adafruit.com/viewtopic.php?t=133614 *Edit...

thank you. right, i would connect the pullup resistors from sda/scl to the 3.3V. is it ok that the i2c parts are powered by 5V while also using pullups connected to 3.3V?

I am using the Teensy 4.0 with two external I2c components. One is the Adafruit MPR121 capacitive touch sensor board and the other is an LCD. I am using Adafruit's library for the MPR121 cap touch board, which uses the "Wire" library which automatically uses the internal pullups?. Both the...

Thanks very much for the info, very appreciated.

Thanks very much for that insight. A better solution than what I had. Sincere Thanks. TonyAm

Yes, the schematic shows a linear regulator, but was thinking about using a buck converter instead. 470nF might have been a typo, I will check. Thank you for pointing that out!

Sincere thanks for reading. Would using a 9V to 5V buck converter be more suitable in my schematic? I'm using the Teensy 4.0 and the Audio board RevD2. Any recommendations for a proper buck converter? The headers marked U7, U8 are where I'll be connecting a 10k audio volume pot (U7) and a 1/4"...

Thanks very much for the great help on this, very much appreciated. TonyAm

Is it ok to connect AGND to GND the way I did in the schematic? Thanks.

Thank you. I did use the tall headers on the first board that I put together and has the same problem. I will investigate this possibility. Edit: Ok, when carefully inspecting the two boards nothing is contacting in a short, all separated. Originally I used the Rev D2 audio board (which was...

Right, thank you. Here it is on top of the Audio Board Rev D from Amazon.

Hello, Thank you for reading. I bought a Teensy 4.0 and Audio Board Rev. D from Amazon and been having problems with my custom PCB audio circuit, whereas previously I did not. I noticed that on the Teensy 4.0 purchased from Amazon it had "NXP" printed on the chip, where the previous Teensy 4.0...

Thanks very much for the great info, I appreciate it. TonyAm

Thanks for reading. I'm using the Teensy 4.0 with the audio adapter board rev d. This is a simple synth using 2 adafruit MPR121 capacitive touch sensor boards that trigger synth notes. Scale, key, octave, wave form are selected via an LCD menu. 1. Should all of the ground pins be connected? 2...

Thank you. I hooked everything up and all is good. Thank you for the info you included here, I appreciate this!

Thank you. I'm planning to use two I2C accessories; an LCD and the Adafruit MPR121 Capacitive touch sensor board. Should I use separate I2C pins (SCL, SDA) on the Teensy 4.0? (i.e., SCL0, SDA0 for the LCD, and SCL1, SDA1 for the MPR121 cap touch board?) I'm also planning to use the Teensy Audio...

Would using a 1M resistor here be useful for an anti-popping solution caused by a mechanical toggle switch? Thank you.

Updated the schematic with negative center power plug and 3PDT bypass switch. (I think I will just cut the trace that connects the "5V" pads to isolate the USB power from external 5V power supply.) Could use checking of my updated schematic if anyone can would be greatly appreciated. Sincere...

Thanks very much. I think I will do what you say; "You should isolate the regulator 5V output from the USB 5V source." I guess with a diode. And leave the Teensy/Audio shield in-circuit when programming. Extra copper or Thru-hole device is a great suggestion. Edit: Just re-read what you...

I'll be removing the Teensy + audio board from the circuit whenever I program the Teensy. Is there something I'm not seeing in my schematic concerning the 5V input from the 7805 regulator? (I do often not notice obvious things when constantly looking at the same schematic for a long time.)...

Thank you. Will check out your stereo buffer, appreciate it.

Thanks very much for that great info. I won't be using the usb port for power. This schematic is a preliminary design, but yes a bypass switch and a negative center power adapter plug is the electric guitar way to go. Appreciate the help, thank you.

Really, no need for any buffer? Also, I have a passive filter circuit for the output as in the schematic attached, does it need to be connected to Out Gnd? Thanks very much, Tony

I'm experimenting. Would I need to add a pre-amp or op-amp buffer circuit before trying to connect a guitar straight into Lin of the audio shield? Would anyone know of a simple schematic for this? Sincere thanks, TonyAme

In case anyone else is following this thread, I have one possible solution for a tone control added to the above audio output line schematic; I know volume controls are usually log type, however I have found the linear to sound better. (C15 will be determined via...

I've been using this audio output circuit for the Arduino Nano Auduino Synth, and for the Teensy Audio Shield. Looking for advice on a possible adjustable tone circuit. Maybe replace R11 with a pot? Any advice/suggestions/comments would be appreciated. Sincere Thanks, TonyAme

Understood. And will will move R3 to the signal leg of the photoresistor jack J11. Move C3 closer to Teensy. Thank you MarkT for; "BAT54S (dual Schottky's in series) for such protection of a single line..." I think I got it now. Sincere thanks for the info on this. Appreciated, TonyAme

Working on a possible way to protect an analog input pin (pin 17) from over or under voltages. Just need to determine the values of the Schottky diodes to use. (The jack J11 will receive a CdS resistive photosensor whose resistive value would be added to that of the pot VR3, (when switched on by...

In case anyone else should find this thread to be of value I have been researching ways to protect the analog input pins of the Teensy from going below GND or above 3.3V if using a resistive sensor as in my circuit above. I've been finding that the use of diodes, either Schottky or all purpose...

The J9-J12 will be used for plugging in a photocell sensor that is wired to plug into female RCA jack. I do this kind of thing with Arduino Nano's, but never before with a Teensy. It adds a fun, unexpected element to the sound. Yup, I should find out what kind of protection circuit to add to the...

Updated schematic for Teensy Audio board. If anyone could use this schematic for their own project, please feel free. (Also, would be great if anyone could point out any potential problems, or make suggestions). I have RCA jacks, which will connect CdS photo-resistive sensors to the analog...

I noticed that on the Audio Shield diagram REV D (for Teensy 4.0), that all of the audio input and output (line level) gnd's are connected together? I've also updated my shem, see attached image. (I might still be "missing the boat" on the audio ground, please let me know). Sincere Thanks.